Control valve



Oct. 5, 1937. F. w. SMITH ET AL CONTROL VALVE Filed Nov. 20, 1935 INVENTOR FRANK w. SM/TH.

BY WILL/AM SHANE.

AT'II'ORNEY Patented Oct. 5, 1937 Ni'iid SATES gears? rst o.

CONTROL VALVE Application November 20, 1935, Serial No. 50,692

8 Claims.

This invention relates to boilers and particularly to apparatus for automatically discharging moisture, scale, sediment or other impurities therefrom.

In the operation of steam generating boilers, scale and sediment are deposited from the water and the amount of impurities that must be discharged to maintain the boiler in a safe and proper operating condition varies substantially with the rate of evaporation. Heretofore it has been customary for the fireman to periodically open a bloW-ofl' connection to discharge these impurities from the boiler, but unless the fireman conscientiously attends to this duty, at proper intervals with due regard to the rate of operation of the boiler, its operative condition will be deleteriously affected due to accumulation of impurities therein.

The object of the present invention is to provide for automatic discharge of sediment, scale and impurities from a boiler in accordance with the rate of flow of steam to the superheater associated therewith.

In the drawing:

Figure 1 is a diagrammatic side elevational View of a locomotive boiler embodying the invention; 7

Figure 2 is a vertical sectional view of the valve that controls the boiler discharge connection together with its operating mechanism; and

Figure 3 is a fragmentary view similar to Figure 1 illustrating another adaptation of the control valve.

Referring to Figures 1 and 2, the numeral l designates the boiler of a locomotive having a drain connection I! communicating with the lower portion of the mud ring for discharging scale, sediment and'other impurities that collect therein. Interposed in drain connection H is a valve I2 comprising a sleeve member l3 open at one end to the valve chamber and adapted to uncover successively a plurality of ports l4 communicating with an annular pocket into which the fluid discharge flows from the mud ring. The fluid passes from the interior of sleeve !3 through apertures i6 and around the valve disc I I when the latter is moved from its seat. The ports l4 formed in the wall of the valve chamber are spaced axially and circumferentially thereof so that a graduated flow is obtained depending upon the extent of opening movement of the valve sleeve It.

The valve stem I8 extends into a piston cham ber and is connected to a piston 2! subjected 55 on one side to the pressure of steam generated in the boiler and to superheated steam pressure through pipes 22, 23 connected, respectively, to the turret 24 and the outlet header of a superheater 25 associated with the boiler. A spring 26 acts on the valve stem to bias the valve toward closed position and provide for a graduated opening movement thereof. A front end throttle 30 (such as described in Patent 1,209,117, issued on. December 19th, 1910, to J. S. Chambers) is 10- cated between the outlet header of superheater 25 and steam pipes 3| .to control the flow of steam to the engine cylinders.

The force exerted on'piston 2! to open the valve is the diiferential between the saturated and superheated steam pressures, or the pressure drop through the superheater, which is a measure of the rate at which steam is being used. Under static conditions, or at low rates of operation, the saturated and superheated steam pressures are substantially the same and the valve remains closed. This is because pressure is always maintained in pipe 23 when the boiler is steaming even though the throttle is closed, in which event the pressures at opposite sides of piston 2i become equalized. With increasing loads the pressure of the superheated steam decreases while that of the saturated steam remains substantially constant and spring 26 may be arranged to oppose the diiferential pressure acting on piston 2i so that the valve cracks open at three pounds, for

. example, and reaches maximum opening at, say, twelve pounds. Accordingly, as the amount of scale and sediment deposited increases with increased evaporating rates, the valve is automatically opened to an extent corresponding with the rate of steamvflow through the superheater so that the discharge may be approximately equivalent to the rate of evaporation and accumulation of impurities.

In the arrangement shown in Figure 3, the valve I2 controls a discharge connection 21 from a steam drier 28 in which moisture and impurities are separated from the saturated steam. With increasing loads, as indicated by increased pressure drop through the superheater, the valve opens correspondingly to accommodate the greater amounts of moisture and impurities to be discharged and also acts to prevent undue loss of steam at lower loads.

We claim:

1. In a boiler having a superheater receiving steam therefrom and a connection for discharging moisture and impurities from the boiler; a valve controlling said connection; means acting to close said valve; and means responsive to the Pre sure drop through the superheater acting to open said valve in accordance With the rate of steam flow through said superheater.

2. In a boiler having a mud ring or the like in which scale, sediment and other impurities accumulate during generation of steam in the boiler, a drain connection to the mud ring, and a superheater receiving steam from the boiler; a valve in said drain connection; a piston for operating said valve; means biasing said valve toward closed position; and piping subjecting said piston to the opposing pressures of saturated and superheated steam and connected that said valve is caused to open in proportion to the pressure drop through the superheater.

3. In a boiler provided with a steam drier, a drain connection to said drier for discharging moisture and impurities separated from the steam, and a superheater receiving steam from the boiler; a valve in said drain connection; a piston for operating said valve; means biasing said valve toward closed position; and piping subjecting said piston to the opposing pressures of saturated and superheated steam and so'connected that said valve is caused to open in proportion to the pressure drop through the superheater.

4. In a boiler having a superheater receiving steam therefrom and 'a connection for discharging sediment, moisture or other impurities from the boiler; a valve controlling said connection; a piston chamber; a piston in said chamber connected to said valve; a connection between said superheater and said chamber at one side of the piston therein for causing the pressure of superheated steam to close said valve; a connection between said boiler and said chamber at the other side of said piston therein for causing the pressure of steam generated in said boiler to open said valve; and a spring biasing said valve toward closed position and so acting that opening thereof is in accordance with the differential existing between the pressures of saturated steam and superheated steam.

5. The method of operating a steam locomotive boiler, which comprises discharging Water and sludge from the boiler Whenever and only when steam is being delivered from the boiler to the operating cylinders in excess of a predetermined rate. a

6. The method of operating a steam locomotive boiler, which comprises actuating a discharge of sludge water from the boiler by the pressure of steam withdrawn from the steam space Within the boiler and effecting such withdrawal of steam to actuate a discharge of sludge water whenever and only when steam is being delivered from the boiler to the operating cylinders in excess of a predetermined rate.

7. The method of blowing off locomotive boilers which comprises automatically discharging boiler water from the boiler only when the steam throttle is opened beyond a predetermined amount.

8. In. combination with apparatus receiving steam from a boiler; a blow-down valve for discharging scale, sediment and other impurities that accumulate in the boiler; adjustable control means for variably regulating the flow of steam from said boiler to said apparatus; and means, responsive to adjustment of said control means, for opening said valve when-steam is supplied to said apparatus in excess of a predetermined rate.

FRANK W. SMITH. WILLIAM SHANE. 

